Investigating microstructural evolution at the interface of friction stir weld and diffusion bond of Al and Mg alloys

Dissimilar Friction stir (FS) and Diffusion bond (DB) welds of Al alloy 5083 and Mg alloy AZ31 were produced at similar peak and bonding temperature of 435 degrees C. The weld had an irregular shaped region in the weld center of DB weld and layered interface in FS weld, having a different microstructure and hardness from the two base materials. The irregular shaped region in DB weld and interface of Mg and Al, in FS weld contained a large volume of intermetallic compound Al12Mg17 and showed significantly higher hardness in the weld center. The present study suggests that constitutional liquation resulted in the intermetallic compound (IMC) Al12Mg17 in the weld center. (C) 2019 The Authors. Published by Elsevier B.V.